There are countless instances where animals have wandered into spaces or areas occupied by humans or vice versa with devastating consequences to the animal or to the human. It should suffice to simply reflect on the number of animal carcasses littering highways as a result of the animal running or darting into the path of a moving vehicle. This is perhaps the most common example and it is this problem to which the present invention principally relates. However, there are other applications. Hunters and campers can be intruded upon by animals wandering into their tents or campsites. In an urban setting, postmen and metermen traditionally encounter threatening animals in their work. Still further, farmers and ranchers have need to set aside certain areas where unwanted animal intrusion does not occur.
The prior art has recognized this problem and certain devices have been produced which relate generally to the subject matter of the present invention. It is known that animals, or at least many animals, can detect ultrasonic sound waves and use the ultrasonic sound waves to detect the source of the sound. Conceptually this is illustrated in FIG. 1 by an object 1 emitting an ultrasonic sound wave designated by reference numeral 2 at a given frequency which animal 3 hears. Ultrasound wave 2 includes waves 2a and 2b which reflect or bounce off stationary objects such as trees 4a and 4b and are reflected as shown to the ears of animal 3. Animal 3 is believed to discern the time lag resulting from the increased reflective distances of waves 2a, 2b to locate the position of object 1.
Utilizing this concept, mechanical devices have been proposed which generate ultrasonic sounds which vary in frequency. Because the ultrasonic sounds vary in frequency or alternatively stated, vary in wave length, the animal is believed to try to locate the sound by attempting to discern the time lag resulting from non-existent reflective waves, which "time lag" results from the varying frequencies of the ultrasonic sounds emitted by the mechanical device. The animal thus becomes confused while it tries to spatially reconstruct the position from which the sound emanates. Tests have shown that the animal is dispersed or leaves the vicinity from which the sound emanates because it is confused. In any event, the animal does not inadvertently move towards the sound. Significantly, the animal is not injured by the ultrasonic sound waves nor is its hearing impaired.
One mechanical device operating on this principle is currently available under the brand name of DAZZLER. The device is mechanical and adapted for hand-held applications, specifically one in which a postman or a meterman would use the device to ward off a dog attack. However, the ability of any mechanical device to generate consistent, repeatable sounds in an intense manner is limited. The durability of any mechanical device is questionable. Significantly, devices which mechanically produce sound waves have inherent limitations in their ability to precisely produce closely controlled sound waves. As of the date of this application, tests are still being conducted on such devices including that of the present invention. It is possible that close control of the wavelenths of the ultrasonic wave becomes much more critical in an application where a moving object, i.e., an automobile, is involved than that involving a standing or slow-moving object.